Navigate Our Web Site Solid Earth Geophysics Geothermal Gravity Habitat Magnetics Natural Hazards Topography -------- People Products -------- What's New Data Tools SEG Index SEG FTP site World Data Center for SEG -------- NOAA's National Data Centers NGDC Home Paleoclimatology Marine Geology & Geophysics Solar-Terrestrial Physics

How to Choose a GIS? A Prototype Generalized Methodology

(An unofficial personal view by David Hastings, from his book Geographic Information Systems: A Tool for Geoscience Data Analysis and Interpretation)

1. Introduction

In my travels with GIS, I see many managers thinking that they may need this new technology, but don't know where to turn for advice. The most available people are vendors of GIS software, but we all know what happens from listening only to sales people. Unfortunately, our peers may be well versed only in the systems that they themselves use; so they aren't necessarily much help either - unless we ourselves are capable of evaluating their standpoint vis a vis our own.

2. Getting a system that does what you need

As in other rapidly evolving fields, there is confusion about GIS on several fronts:

• What is the basic definition of the term GIS?
• What is desirable in a GIS?
• What are our requirements for a GIS?
• What is currently available in GISs, at what system cost (hardware and software at initial purchase, hardware and software maintenance costs) and administrative cost (training, scientific and technical support needs, time to perform certain specific tasks, etc.)?
• What packages are in the market? Do they (choose one below):
  • do what we want, and do it well?
  • work well, but are inappropriately designed for our needs?
  • work well and are appropriately designed, but are not sufficiently powerful, or have clumsy data structures or user interfaces, or have too steep a learning curve for our occasional needs?
  • not work well?

Partly because of

• the plethora of choices in the industry,
• the rapid advance of the technology,
• the absence of any single complete GIS, let alone a choice of complete GISs,
• the non-GIS graphics, mapping, image processing, or other software that is sometimes sold as GIS (just as there is vaporware in other fields of computer science),
• the desire among managers to jump into such a field as a "solution to all their problems" without themselves becoming adequately educated in the field,

there are some salespeople and consultants who will help "guide" you to their favorite system, whether or not it is appropriate for you.

So the question becomes: "How to avoid buying an expensive non-solution for your needs?"

3. What is a basic definition of the term GIS?

Click here for the definitions that appear elsewhere on these pages.

4. What do you want from your GIS? How do you determine your needs?

• It is easy to agree with a salesperson's recipe for your operations. But you know what you get with this method.
• It's also easy to talk with a GIS specialist/consultant. However, with many dozen available GISs, that specialist is likely to be biased by his/her own background.

If you are an environmental scientist, your needs are more complex than can be satisfied by the stereotypical urban planner's system. The latter's system is often designed to produce beautiful line plots to meet certain specifications, rather than to help with scientific analysis. You may wind up with a system that can give you a map of power lines in a county, but you can't model the environmental impact of a new spur to one of those power lines, or you cannot model the effect of a future El Niño on the need for food aid in the Sahel.

In practice, it is useful to talk with salespeople. They are a ready source of information, despite their obvious bias toward their own system. Likewise with GIS specialists. In the end, however, there is nothing like one's own knowledge. Textbooks, special conference volumes, technical meetings, journals are all available. Then get your hands dirty on some systems. Not just keyboard access at a commercial exhibit at a professional meeting, but formal training and simulation of your working environment. You wouldn't expect any less than this in other fields (like buying a car); you can't expect to become conversant in GIS any easier.

If you want to get your hands dirty in an easier fashion, get a copy of an educational GIS package. There are several of these. Some are very simple, with few "bells and whistles" but a good cross-section of basic GIS functions, accompanied by a training manual and sample exercises. Others may be more substantial, allowing you to actually do research and environmental monitoring while you train yourself in GIS technology.

After spending some time learning about GIS, you will be better able to evaluate your needs than if you just accept salespeople and consultants as your gurus.

After such self-education, and a chance to reflect, you may discover that many GISs are inappropriate for your needs.

• Some GISs are little more than mapping packages with selective retrieval, editing, and plotting facilities. Conversely, some are little more than embellished image processing or visualization software;
• Some GISs have nonexistent, inaccurate, or misleading georeferencing;
• Some GISs fail to combine the benefits of both vector and raster data structures;
• Some GISs cannot process data with their original scientific values or accuracies, but only fully handle class values of 0 to 255;
• Some GISs inadequately protect data integrity (e.g. they don't automatically back up your input data while a process is run).
• Some GISs have quirky or nonexistent work flow for many types of applications; and/or
• Many GISs don't provide you with source code or adequate understanding of their inner workings. Some GISs are difficult to enhance with the functions that they lack, but which you need or desire. (Remember that no GIS is complete, so you WILL want or need to enhance them, or live with their shortcomings.)
• Many GISs promote themselves for broad-based use, but most have actually emphasized certain types of user communities in their development and marketing. Are the "de-facto" areas of emphasis of a particular GIS compatible with your needs? Might these areas of emphasis possibly help or hinder you, when you need help? Alternatively, might your mission/interests be an asset to a particular developer/vendor, that might bring you a particularly fruitful working relationship?

5. How to acquire "the best GIS for you?"

GIS software systems, hardware environments that support such systems, and services such as data base development, systems integration, consulting, and special-purpose publishers are proliferating faster than one can keep track of them. Likewise, systems and vendors are disappearing or repositioning themselves at an unnerving pace. In the middle of all this entropy is real and exciting progress in computer systems and GIS capabilities - if we can only sort the real progress from the vaporware.

No list of recommendations can be complete and current. Indeed, as vaporware vs. real systems may be relative to one's intended applications, it is impossible to make recommendations based on speculation or generalizations. In other words, one person's apparent vaporware may be another person's optimal system.

The best way to learn about available/appropriate systems is to dive in with both feet, with the help of expert friends, professional society journals and meetings, etc. ==> and to become an expert yourself. One viable alternative is to hire a trustworthy consultant. But how to find such a consultant? The same way that you find a good dentist (after getting several imperfect "drillings" from unsuccessful candidates), car mechanic, or lawyer! (If you go the consultant route, assume that consultant will be familiar with - and have commercial ties to - only a few of the more popular GISs, rather than the GIS with the best features for you.)

This may help you start the process:

• Study the Yearbook of the American Society of Photogrammetry and Remote Sensing, which published mildly informative abstracts of its corporate sponsors. This does not have complete coverage of the market, but does give a broad perspective of what's available. Also check the ads in Photogrammetric Engineering and Remote Sensing, of which the Yearbook is a mid-summer issue.
• Peruse the annual survey of GISs published by the trade newsmagazine GIS World. Brief and uncritical of shortcomings of systems, this may bring out some systems that you had not heard of previously.
• Acquire one of the public domain, freeware or low cost systems (like
  • the public domain GRASS,
  • or its commercial cousin GRASSLAND [which has commercial and freeware adaptations of GRASS, and supports the public domain version of GRASS as well],
  • the freeware OSU MAP for the PC [valuable for intruductory training and certain small projects],
  • or Idrisi)
  and become familiar with their capabilities and limitations. Some of these systems are substantial ==> they may serve your needs. Some modern public-domain or low-cost systems may give you as much support as commercial systems, especially if you participate in users fora or your applications are not within the mainstream of the user community. (If you are doing environmental science with GIS, assume that you are NOT in the mainstream of some GISs. This trend is changing for the better. But caution is still needed.) Most GISs have their mainstream firmly planted in the urban/regional planning communities. Many of these uses are oriented around "sophisticated cartography" rather than "sophisticated numerical analysis/modeling or resources/environmental issues." Ask vendors for references in the environmental science community, contact these references, and find out how they make do with the software.
• Go to professional meetings and live in the exhibits.
  • Go to all the vendors' booths.
  • Get as thorough a demo of each candidate system as possible.
  • Talk to as many customers of such systems as possible.
  • After narrowing down the systems based on functionality, price, hardware environments, openness to revision and personal enhancements (source code available?), take training in the systems on your short list. Arrange to actually use the systems in situations like your own.
  • Ask if the vendor has a short-term trial license for its software, combined with data and tutorial materials in your field. Vendors that have such facilities may actually cater to your type of work.
  • Will you be a casual user, or will you have an intensive daily need for high-powered GIS? If the former, get a user-friendly system. If the latter, try a simple user-friendly system that you plan to outgrow. By the time you outgrow it, you will know what you want, and will be able to see through the tricks of advertising and "canned" demonstrations.

In the end, the low-cost or public domain, user-friendly system may prove adequate for your needs. Or its shortcomings may be no greater than those of the competition.

Does this sound like a lot of work? You bet! There are few short cuts. Thus, many people acquire systems without truly understanding the options. If you do the same because you don't "have the time" to adequately investigate the alternatives, you may have plenty of company to share stories with!

Go to the CyberInstitute Short Course on GIS.

For information about this document please contact: